1. Technical Field of the Invention
This invention relates generally to signal processing and more particularly to determining signal strength of a signal.
2. Description of Related Art
As is known, wireless communication devices (e.g., a radio receiver) may tune to receive a selected radio frequency (RF) signal from within a frequency band of interest. For example, a frequency modulated (FM) radio receiver has a frequency band of interest from approximately 76 MHz to 108 MHz, where radio stations transmit on particular frequencies (e.g., 103.5 MHz). Thus, even though the radio receiver is tuned to a particular channel (e.g., 103.5 MHz), it has to be capable of receiving the entire frequency band of interest. This may present an issue if the signal strength detection for automatic gain control (AGC) is based on a narrow band signal (e.g., the particular station of 103.5 MHz) and not on the wide band signal (e.g., the frequency band of interest) being received.
For instance, if AGC is based solely on the narrow band signal and the wide band signal includes significant energy outside of the narrow band signal (e.g., outside of the selected channel), the low noise amplifier and/or the analog to digital converter of the radio receiver may saturate, causing an error. Accordingly, most radio receivers include a wide band signal strength detector for the automatic gain control.
As is further known, there are a variety of ways in which a wide band signal strength detector may be implemented. For example, a signal strength detector may be implemented as a peak detector or as an RMS (root mean square) detector. Issues with such detectors include complexity of circuit design, power consumption, accuracy, and bandwidth limitations of signals being detected.
Therefore, a need exists for a method and apparatus of signal detection that overcomes at least one of the above mentioned issues.